As the roaring twenties came to a close, radio technology would continue to evolve with very significant improvements to consumer sets, particularly in the area of shortwave reception. The price of radios would continue to fall as availability continued to increase. Herbert Hoover could have added “a radio in every home” to his famous “a chicken in every pot and a car in every garage” campaign slogan. This radio boom would continue right up until December of 1941, when the first bombs were dropped on Pearl Harbor. After that, new radios would be a scarcity as almost all production and materials were diverted to the war effort.
Let’s go back for a moment to 1935. The US Navy decided that it should have amongst other things, a state of the art receiver for shipboard use. The receiver would have to be able to tune all of the frequencies usable by ships at sea for long distance communication. At the time, this was considered to be 50 kHz to about 30 mHz. It would need to be selective, sensitive and rugged. Enter the National Company Inc.
The National Company began as Stone and Webster Engineering Inc., a supplier of sheet metal materials to the growing power plant industry at the turn of the century. Looking for an addition source of income and already having shops capable of turning out sheet metal products, Warren Hopkins, president of Stone and Webster, along with associates Walter Balke and Rosewell Douglass, incorporated the National Toy Company in October of 1914. They landed their first order with retail giant Woolworth’s and soon secured a patent for the manufacture of talking toys. By 1916 the company was highly successful, supplying toys to F.A.O. Schwarz, Gimbels and others. By the early 1920s the company added radio components to its product line. Soon after, the company dropped the word “Toy” from its name and became “The National Company”.
In 1924, Fred H. Drake and Glenn Browning, both Harvard engineering graduates, developed the Browning Drake tuner which was a combination TRF and regenerative circuit. Browning and Drake approached National to manufacture the tuner and soon a kit radio under the name National Browning Drake was on the market. I’ll feature one as “Radio of The Month” sometime in the future.
Another prominent engineer, James Millen began work as National’s Chief engineer in 1924. Mr. Millen had already established a name for himself writing magazine articles about radio and other technical subjects as far back as 1916 as a way to pay for his education at the Stevens Institute of Technology in Hoboken, N.J.
The company had a degree of success producing a variety of broadcast and first generation short wave receivers between 1924 and 1932. All used TRF or regenerative topologies. In 1932, General Electric was contracted by the Civil Aeronautics Authority (predecessor to the FAA) to design and build a system using short wave radio to communicate with aircraft as the need arose from the growing airlines industry. GE built the transmitters and asked the National Company to design and build the receivers. James Millen chose the superheterodyne circuit to do the job. The result was the National AGS (Aeronautical Ground Station) receiver. It was the first commercial grade, high performance short wave receiver to be mass produced. Most were bought by the government, but a few went to amateur radio operators with deep pockets.
In 1934, Mr. Millen envisioned producing a high end receiver targeted at radio amateurs. His goal was to bring it to market by the holiday season in December of that year. The target was missed due to production problems and material shortages. By 1935, political unrest in Europe and the Pacific rim made the need to advance radio technology a high priority for the military. The US Navy sought bids with less than three months advance notice for an advanced high performance receiver. The National Company’s high tech ham receiver would meet the requirements with some modifications. None the less, completing a prototype in such short time would be a challenge. The engineers nick named it the “HRO”, which stood for "Hell of a Rush Order". The name stuck. The National HRO receiver met the dead line, and outperformed the competition.
With still a few years before the outbreak of war, the radio was not considered a military secret and the company produced a non military version for the consumer market, primarily the amateur radio community. They were expensive. A stripped down version of the radio, less tubes, speaker or power supply retailed for $175. Add those other parts and the price tag could exceed $250, which was a lot of money when the average Joe, if he had work at all, was earning $25 - $50 per week and gasoline was under $.15 per gallon. The basic ham radio version less the accessories sold for $229 and the commercial version for about $320 Both the commercial and military versions were rack mountable, the military version having its components coated with a liberal application of fungus resistant varnish.
By the start of the war, the HRO had evolved into a model known as the RAS, but the National HRO, in one form or another remained in production well into the 1970s. Finally ending its run as a solid state version. Most importantly, the HRO set the stage for what would turn out to be the largest and fastest growth of technology since the start of the industrial age. The pace of technological advancement that would occur in World War Two would be unmatched until the invention of the personal computer in the 1970s.
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A minimum of nine coil sets were required to receive all of the frequencies between 50 kHz and 30 mHz. Normally the radio was ordered with just the coils that the user would require, such as those used for aircraft or ship communication by the military, or commercial frequencies such as a reporter would use for sending news stories back to the U.S. from overseas. Four coil sets were designed to cover the popular amateur bands. 
Here is an HRO as it would have appeared in a rack on board a ship or in a commercial installation. Just above the receiver is storage compartment for holding up to five coil sets. Above that is the speaker.
